This invention relates generally to a baler, and specifically to an improved counterbalancing mechanism for the pickup of a baler.
The instant invention is in the nature of a general improvement over the counterbalancing system disclosed in U.S. Pat. No. 3,984,969. FIG. 1 of that patent shows a dual pivot crank counterbalancing system which requires individual adjustment of the biasing means used to support the weight of the pickup.
Other prior art counterbalancing systems, such as that shown in U.S. Pat. No. 3,798,885, discloses the use of a relatively long low rate tension spring (or a pair of such springs connected in series) disposed parallel and above the baler pickup, and a sheave rotatably supported on the baler above one end of the pickup and a cable and link assembly interconnecting the spring and the one end of the pickup. The cable is connected to one end of the spring and extends horizontally therefrom to and about the sheave and then extends downwardly to its connection with an upper end of the link. The link is pivotally connected at its lower end to the one end of the pickup such that the moment arm of the upward lifting force about the pickup pivot point will increase as the spring load decreases.
While the prior art systems have, in an overall sense, proven to be satisfactory, some disadvantages have been discovered.
One disadvantage relates to the difficulty with which an operator adjusts the counterbalancing forces on the two ends of the pickup. Separate adjustment to obtain equal counterbalancing forces is extremely difficult, and, in reality, never actually obtained.
Another disadvantage of the prior art systems is that they have no practical means of compensating for different deflection of the two pivot cranks. It is very seldom that the forces encountered by the pickup are equally distributed along its length, and thus the ends tend to deflect different amounts. None of the prior art systems take this fact into account by structurally compensating for the absorption of uneven forces.